Copyright © Philip M. Parker, INSEAD. Terms of Use.
| Year | Description |
| 2001 | Invention patented by Gerald J Henderson on February 6th, 2001. Abstract: An electronic abacus calculator comprising an electronic abacus display screen in combination with a numeric display and an electronic keyboard calculator. The invention also comprises a personal abacus, which comprises a mechanical abacus or an electronic abacus calculator or both in a suitable carrying case, which is designed to open and make the abacus available for use in the case. |
| Source: selected by the editor from original sources. | |
Copyright © Philip M. Parker, INSEAD. Terms of Use.